▎ 摘　　要

NOVELTY - Solid electrolyte interphase comprises phosphorus doped reduced graphene oxide nanoparticles. USE - The solid electrolyte interphase is useful to produce cathode for secondary battery including lithium metal battery (preferred), lithium-sulfur battery, lithium-air battery, lithium ion battery, magnesium ion battery, sodium ion battery, potassium ion battery and aluminum ion battery of portable electronic device, mobile unit, power device and energy storage device (all claimed). ADVANTAGE - The solid electrolyte interphase stabilizes electrochemical performance of lithium metal battery, increases coulombic efficiency, charge and discharge capacity, durability, and electrochemical properties, preferably rate of battery. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) producing solid electrolyte interphase, comprising adding phosphoric acid into the graphene oxide powder, heat-treating at 700-900 degrees C under inert gas atmosphere to prepare phosphorus (P) doped reduced graphene oxide; (2) cathode comprising a cathode material thin film, and a protective layer including phosphorus (P) doped reduced graphene oxide nanoparticles formed on the cathode material thin film; (3) producing cathode, comprising (a) preparing a dispersion by dispersing the phosphorus doped reduced graphene oxide nanoparticles in a dispersion medium, (b) immersing the substrate in water, and injecting the dispersion to form the self-assembled molecular film on the surface of the phosphorus doped reduced graphene oxide nanoparticles, (c) preparing a substrate coated with a phosphorus doped reduced graphene oxide film by lifting the substrate from the water surface and transferring the self-assembled molecular film into the substrate, and (d) preparing a cathode in which a phosphorus doped reduced graphene oxide protective layer is formed by transferring the phosphorus doped reduced graphene oxide film on a cathode material thin film; and (4) secondary battery comprising the cathode.